Optical investigations and exciton localization in high quality Zn1−xMgxO–ZnO single quantum wells

This work investigates the photoluminescence properties of Zn1−xMgxO–ZnO single quantum wells, which have been fabricated by molecular-beam epitaxy. With increasing temperature from 13to300K the single quantum well-related emission peaks exhibit an irregular S-shaped (redshift-blueshift-redshift) behavior, which is in contrast with that ascribed to band gap shrinkage (redshift). In order to clarify the origin of this behavior, the temperature dependence of the integral photoluminescence intensity of the quantum well emission was studied and the relevant activation energies were calculated and correlated to its full width at half maximum, band offsets, and monolayer fluctuations.